Sleep and Circadian Rhythm

Question 1

Describe what happens during wakefulness?

Answer 1

Excitatory neurons in the ARAS are released from sleep centres in Reticular Formation which stimulate excitatory pathways in the CNS and PNS. Positive feedback sustains wakefulness in individuals

Question 2

What do EEG recordings show?

Answer 2

Electrical activity in the brain

Question 3

What will an EEG show when a person is relaxed/awake?

Answer 3

High fequency, high amplitude waves (alpha waves)

Question 4

What will an EEG show in an alert, awake state?

Answer 4

High frequency, low amplitude, asynchronous waves (B-Waves)

Question 5

Why is amplitude low in an alert EEG?

Answer 5

Brain is doing lots of things so desynchonised waves cancel each other out = low amplitude, high frequency

Question 6

What are theta waves?

Answer 6

Low frequency, varied amplitude, Common in children, times of emotional distress and during sleep

Question 7

What are delta waves?

Answer 7

Low frequency, high amplitude. Occur in deep sleep

Question 8

Describe stage 1 in the sleep cycle?

Answer 8

Slow wave, non-REM,S-Sleep. Light sleep, easily roused, theta waves

Question 9

Describe stage 2 in the sleep cycle

Answer 9

Eye movements stop, EEG shows sleep spindles (rhythmic waves of roughly 12-14 Hz)

Question 10

Describe stage 3 in the sleep cycle

Answer 10

Delta waves interspersed with short episodes of faster waves, spindle activity declines

Question 11

Describe stage 4 in the sleep cycle

Answer 11

Exclusively delta waves. V difficult to rouse. Sleep talking and sleep talking may occur

Question 12

Describe REM sleep

Answer 12

Rapid Eye Movements occur and dreams may occur.

Question 13

What are the physiological characteristics of deep, slow wave sleep?

Answer 13

Deep sleep occurs in first hours of sleep, most restful sleep type. Associated with decreased vascular tone (BP), respiratory and basic metabolic rate

Question 14

What are the physiological characteristics of REM sleep?

Answer 14

Dreams occur, eye muscles show bursts of rapid activity, all other skeletal muscles ihibited,HR/RR become irregular and brain metabolism increases

Question 15

What occurs in sleep deprivation?

Answer 15

Impairment of cognitive function, physical performance. Sluggishness and irritability

Question 16

What does sleep support?

Answer 16

Neuronal plasticity, learning and memory, cognition, clearance of waste products from CNS, Conservation of whole body energy and immune function

Question 17

Describe insomnia

Answer 17

chronic inability to obtain necessary amount/quantity of sleep to maintain adequate daytime behaviour

Question 18

Describe night terrors

Answer 18

Children thrash and scream or may sit/stand up with eyes open and are not properly awake. Child does not remember the episode on waking the following morning

Question 19

Describe somnambulism

Answer 19

Occurs exclusively in non-REM sleep, mainly in stage 4 sleep

Question 20

Describe narcolepsy

Answer 20

Patients enter directly into REM sleep with little warning. Dysfunctional orexin release from the hypothalamus